Jack.



o. GREBNSTRAN.

JACK.

APPLIGATION FILED AUG. 24, 1909.

962,506, Patented June 28, 1910.

/Mfym` @j ATE?? FFC.

OSCAR GREENSTRAN, OF GRANADA, MINNESOTA.

JACK.

Specification of Letters Patent.

Patented June 28, 1910.

To all whom it may concern:

Be it known that I, OSCAR GREENSTRAN, a citizen of the United States, residing at Granada, in the county of Martin and State of Minnesota, have invented certain new and useful Improvements in Jacks, of which the following is a specification, reference being had to the accompanying drawings.

This invention relates to improvements in cribbing jacks.

The object of the invention is to provide a simple, inexpensive and practical device of this character which will be self-locking when placed in position, and which may be readily adjusted for use in supporting the cribbing or frame-work in the narrow passages of excavations and mines.

Vith the above and other objects in view, the invention consists of novel features of construction and the combination and arrangement of parts hereinafter fully described and claimed, and illustrated in the accompanying drawings in which- Figure 1 is a side elevation of my improved jack showing it in use, the cribbing being shown in section. Figs. 2 and 3 are detail sectional views taken respectively on the lines 2-2 and 3-3 in Fig. 1. Figs. 4 and 5 are perspective views of the two members of the jack.

The jack consists of two members 1, 2 having their inner ends adjustably and'pivotally engaged, and their outer ends provided with jaws 3, 4 to engage the cribbing or frame-work F. The member 1 is channeled longitudinally and consists of two side plates 5, united at their outer ends by a jaw 3, which latter is preferably of rectangular shape and has a slight longitudinal curvature to cause its sharpened end edges to bite the cribbing F. The side pieces or plates 5 are formed with longitudinal slots 7, in one wall of each of which are formed notches, or seats, 8 for the reception of a transverse pivot pin 9 arranged in the inner end of the member 2. The member 2 is preferably formed from a straight, flat bar, the inner end of which is adapted to move between the side ieces 5 of the member 1 and carries the pin 9, the ends of which slide through the slots 7 and are adapted to drop into any one of the seats 8 to lock the two members against longitudinal movement with respect to each other. The other end of the member 2 is enlarged to provide the jaw 4, which latter is the same in construction as the jaw 3. The inner ends of the side pieces 5 of l the member 1 are united by an arched or U- shaped cross piece 10, which forms a locking member, or stop, to limit the swinging movement of the members 1, 2 with respect to each other in one direction. Said cross piece 10 is preferably of arched shape, as shown more clearly in Fig. 4, and in its outer portion is a threaded opening for the reception of a stop screw 11 which forms an adjustable stop. 1n operation the members 1, 2 are swung to angular position with respect to each other after they have been adjusted longitudinally to dispose of their jaws 3, 4 at the required distance to support the cribbing F, and when in such position they are placed between the opposite portions of the cribbing and then straightened to cause the sharp edges of said jaws to bite into the cribbing. As the pivot 9 passes the longitudinal center or axis of the members, the latter become self-locking and will consequently be effectively retained in position to support the cribbing. By adjusting the stop screw 11 the angular position of the two members when in locked position may be varied according to requirements when the device is used in different positions and in different kinds of cribbing.

From the foregoing it will be seen that the invention provides an exceedingly simple and practical device of this character which may be produced at a small cost and will be strong and durable in use, and the parts of which may be readily adjusted for diierent kinds of work.

Having thus described the invention what I claim is:

1. A jack, comprising a channeled member having longitudinally slotted side pieces, the walls of said slots being formed with seats, a second member having a transverse pin movable through the slots in said side pieces and arranged to engage said seats, a cross piece uniting the inner ends of the side pieces of the channeled member, and a stop screw in said cross piece arranged to engage the second member.

2. A jack, comprising a channeled member having longitudinally slotted side pieces,the

Walls of Said Slots being formed With seats, said channeled member, and a jaw 'at the a second member having a transverse pin outer` end of the second member. i 10 movable through the slots in said side In testimony whereof I hereunto aix my pieces and arranged to engage said seats, vsignature in the presence of two Witnesses.

an arched cross piece uniting the inner ends OSCAR GREENSTRAN. of the side pieces of the channeled member, Witnesses: a stop screw in said arched cross piece, a jaw REX W. GARRETr,

unitin'githe outer ends of the side pieces of A. A. LINDAHL. 

